Grab for heapable material



April 24, 1934. P. NEFFENDORF, GEN GAERTNER 1,956,079

GRAB FOR HEAPABLE MATERIAL Original Filed April 26, 1950 2 SheetsSheet l April 1934- P. NEFFENDORF, GEN GAERTNER GRAB FOR HEAPABLE MATERIAL Original Fil Apr 26, 1930 2 Sheets-Sheei 2 Patented Apr. 24, 1934 UNETED STAT with]? GRAB FOR HEAPABLE MATERIAL Paul Neffendorf, gen.

Gaertner, Vlaardingen,

()riginal application April 26, 1930, Serial No.

447,725. Divided and this application June 27,

1931, Serial No. 547,329

4 Claims.

This application is a division of application Ser. No. 447,725 filed April 26, 1930 which relates to grabs for heapable material, in which the closing rods arranged at the grab head are hingedly connected at their outer ends to the grab buckets, and the buckets are hingedly connected the one with the other by side arms fixed on the buckets. Also according to the parent application the side arms of the grab are extended beyond the points on which these closing ropes act, the closing ropes being arranged and guided in such a manner that, when the grab is open, they exert an upward pull on the arms and when the grab is closed, they pull in a horizontal direction.

' This effect is obtained by guiding the bight of the closing rope, connecting the two points at which the closing rope acts on the side arms of the grab, over rope pulleys, which hold the closing rope raised in the middle of the grab'when the grab is open.

The arrangements according to the parent application are chiefly suitable if the winch for the closing ropesand also the winch for the opening ropes have each a reversible drive, as is generally the case in elastic drive.

This-invention relates t-o a special-arrangement of grabs according to the parent application, for the operation of which such winches are designed, the'driving-mechanism of which is either notreversible at all or only to a certain extent.

Thewinch driving mechanism is in this case ready revolving drum.

steam operated, and the grab,'when opening, generally has to rotate the drum of the closing ropes or to accelerate the revolving speed of the al- The invention consists in that, in grabs for :heapable material asdescribed and shown in the parent application the opening rope orthe pair of opening ropes runs over pulleys on the commonhinge point of the pair of toggle levers which act on: the grab rods and initiate the opening .movement of thegrab or on a memberattached to said hinge point,'and ends on the grab head.

In a guiding of the opening ropes of this kind atv the tightening of the opening ropesof the grab forces are produced, owing to the fact that the grab head and the hinge point of the toggle levers are approached the one to the other, which initiate the opening movement of the grab, and which; act on the closing ropes through the intermediary of the side arms or" the grab buckets and unwind the-ropes off the drum.

If the arrangement is made so that the opening rope or the pair of opening. ropes forms or form at. the same time a pulley block connection between the grab head and the axle of the pulley for changing direction of run for the closing ropes, also a direct pull is also exerted on the closing ropes in that their horizontally extending bight is pulled upwards.

The invention relates further to the separate means, for instance stops, for limiting, during the opening movement of the grab, the approaching of the hinge point of the pair of toggle levers or of the axle of the pulley for changing direction of rope to the grab head at the moment at which the common hinge point of the grab bucket arms arrives in the imaginary plane extending through the points on which the grab rods act on the grab buckets.

By this means the pulling efiect between grab head and the bending point of the toggle lever system or of the axle of the pulley for changing direction of rope for the closing rope ceases the moment, the side arms of the grab buckets exert their maximum weight effect upon the closing ropes and this sheet alone is suflicient to chest the further movement of the closing ropes until the grab has attained its extreme position in the opened state.

A specially simple and favourable embodiment of the new inventive idea is obtained, if an intermediate element is used for the connection between the bending point of the toggle lever pair or the pulley axle and the opening rope or pair of opening ropes, which element is fitted with a running block for the opening rope or pair of opening ropes, and if the length of this intermediate element as well as the position of the points at which the ends of the opening ropes are attached to the grab head are selected so that the pulley block effect of the opening rope or of the pair of opening ropes ceases automati cally when the grab assumes a position such as that shown in Fig. l.

According to the invention the new proposals may be employed singly or groupwise, or all together also on grabs which comprise more than two grab buckets or claws usually arranged in star shape relative to the grab head.

A form of construction of a grab according to the parent application with the guiding for the opening ropes according to this invention is illustrated by way of example in the accompanying drawings.

Fig. l is a side elevation of the closed grab.

Fig. 2 is a similar View, partly in section.

Figs. 3 and 4-. show in side elevation two different intermediate positions of the grab during an opening or closing proceeding.

Fig. 5 is a side elevation of the normally opened grab.

Fig. 6 is a side elevation of the excessively opened grab (in a position specially favourable for trimming work).

The grab constructed according to the main patent application comprises grab buckets a with side arms I) hingedly connected at their ends at c, a grab head n, grab rods e hinged on the grab head at rl and on the grab buckets at f. A pair of toggle levers h engage at i on the grab rods e. The joint 7c of the toggle levers is supported by an opening rope m (or by a pair of opening ropes). Closing ropes q (Fig. 6) one end or" each of which is fixed to a rope equalizer 7c are guided over pulleys on axles v in the side arms I) and along pulleys p on the axles d by which the grab rods e are hinged on the grab head n.

The grab according to the invention operates in the following manner:

In closed condition it assumes the position illustrated in Figs. 1 and 2 in which the grab buckets are held closed by the closing ropes engaging on the axles v.

If it is desired to open the grab either the closing ropes are released or the opening ropes m are pulled. Thus, owing to the pulley block effect of the closing ropes m the pair of toggle levers h are spread in that the axle 7c, the common hinge point of the levers h, is moved towards the grab head. Owing to the spreading of the pair of toggle levers h the grab rods e are likewise spread so that the grab opens and assumes successively the positions illustrated in Figs. 3, 4, 5 and 6. During this movement the following peculiar operations take place:

As soon as the grab has opened a certain distance according to the above described details of the opening movement the grab arms b act by gravity. A position in which this eiiect already takes place is illustrated in Fig. 3. Under the action of the weight of the arms h and the simultaneous action of the spreading levers h the slack closing ropes are pulled so that they do not ofier any obstacle for the opening of the grab.

During its opening movement, the grab then comes into a position in which the hinge point e of the grab arms b is situated at the same height as the suspension points f of the grab buckets on the grab rods e. At this instant almost the entire weight of the heavy grab arms 1) becomes operative. If this weight were free to act the grab would receive a heavy jar which however must be avoided in View of the durability of the grab and of the supporting ropes and especially of the crane frame. The braking of the opening movement of the grab is effected according to the invention free from shock by the peculiar cooperation of the pulley block connection of the supporting rope m and of the lever mechanism formed by the grab.

In the position shown in Fig. 3 the pulley block between the grab head it and the h ge point Ic is pulled so far into the grab head that the bights of the two ropes m assume an approximately horizontal position. It is not possible to pull the pulley block further into the grab head because the lower hinge points 1 of the grab rods 6 are in the outermost position which they can assume in the lever mechanism formed by the grab. If from this position on the hinge point 0 the grab arms I) move in downward direction through the horizontal plane formed by the hinge points 1, the two hinge points f again approach one another. Thus, the toggle levers h are again pressed downwards so that the common hinge point lc moves away from the grab head it (see the position of the grab lever mechanism illustrated in Fig. 5). During this movement the pulley block connection of the rope m is tensioned and the grab head n first lifted. If the grab arms b move still further in downward direction, the holding ropes m are pulled, owing to the movement of the grab head which moves upwards away from the hinge point so that the whole grab is slightly lifted, the distance through which the whole grab is lifted being dependent upon the length of levers chosen of the entire grab system and upon the fixing points 101" or" the rope m on the grab head. Owing to the above described effect of the pulley block connection in the conjunction with the peculiar movements of the grab head relative to the hinge point It, the desired braking of the opening movement of the grab takes place in a gentle manner Without sudden stressing of the ropes and of the crane system on which the grab is suspended; the gentle braking of the opening movement of the grab, which without this braking would take place suddenly, is now effected in the grab system proper. The braking is caused by a skillful utilization of elements which are in any case necessary for the moving of the grab, without the introduction of complicated hydraulic or pneumatic brakes which considerably increase the Weight of the grab and such as have already been proposed for braking the opening movement of large grabs.

This grab has in the form of construction shown a guiding for the opening ropes m, in which these opening ropes m are guided over running blocks mounted on the upper end of a connecting element m". The lower end of this connecting element m is connected to the common hinge point of the toggle levers h, at which point also the axle k for changing direction of the closing ropes q is arranged. The ends of the opening ropes are attached at m in the grab head 12 and so, that in the position of the grab shown in Fig. 4 (in which the points 0 and f are situated on a straight line) the points m are approximately situated in the plane of the lower edge of the pulleys of the running block.

In this form of construction the intermediate element m" forms a peculiar connection between the opening ropes m and the closing ropes q and a connection between the toggle levers h and the grab head n, the lower ends of the opening ropes in forming a portion of this connection.

Each of the two closing ropes (1 runs from the crane first over the guide pulleys 19 mounted on axles d in the grab head. Each rope q then runs under pulleys on axles v on the grab arms I), then over pulleys on the hinge point It to a pulley on the second axle c of the other grab arm 13, the end of each closing rope being fixed to the rope equalizer k. This rope equalizer is con structed in known manner as a small rope drum which is suspended hanging freely from the hinge k of the toggle levers h.

The new opening rope guiding operates as follows:

In the closed position of the grab (Figs. 1 and 2) the intermediate element m is in its lowest position. At'the tightening of the opening ropes m the bending point of the toggle levers h and the grab head 12 are approached the one to the other by the pulley block effect, however only until the position shown in Fig. 4 has been reached. From this position the arms b of the grab with the buckets a bend in downward direction under the action of their weight, the loose closing ropes q, which already at the beginning of the opening movement at the transition (from the position shown in Figs. 1 and 2 into the positions shown in Figs. 3 and 4) have been pulled along, are still further pulled through (Figs. 5 and 6). The opening ropes m and the element m" assume then little by little again a lower position, a soft braking effect being obtained by the peculiar cooperation of the closing ropes q with the opening ropes m upon the arms I) passing through the intermediate position of the Fig. 4. In this manner an assuming of the open position free of shocks is obtained even with unsupported grab.

Stops a: are further arranged one on each side of the grab head n and the grab rods 6 bear against these stops in order to prevent the pulley axle 70 forming the common hinge point of the toggle levers h from moving further towards the grab head n when in the position shown in Fig. 4, so that then the grab head hangs so to say directly on the opening ropes m.

I claim:

1. An opening rope guiding for grabs for heapable material, comprising in combination a grab head, grab buckets, two rods each connecting one grab bucket to said grab head, a pair of toggle levers connecting said two rods, side arms of said grab buckets, a hinge connecting the inner ends of said side arms, closing ropes acting upon said side arms, opening ropes acting upon said rods forming a pulley block connection between said grab head and the common hinge point of said toggle levers.

2. An opening rope guiding for grabs for heapable material as specified in claim 1, comprising in combination with the grab head and the opening ropes, of a pulley for changing direction of said ropes, and an axle of said pulley.

3. An opening rope guiding for grabs for heapable material as specified in claim 1, comprising in combination with the grab buckets the side arms of said grab buckets hingedly connected at their inner ends, the grab head, the rods connecting said grab buckets to said grab head, the toggle levers hingedly connected to said rods, of a pulley axle serving as a hinge connecting the inner ends of said toggle levers.

4. An opening rope guiding for grabs for heapable material as specified in claim 1, comprising in combination with the arms of said grab bucket, the grab rods, the grab head, the opening ropes attached to said grab head, the toggle levers and the axle for the guide pulley for the opening ropes forming the hinge point of said toggle levers, stops one on each side of said grab head, an intermediate element upwardly extending from said axle, running blocks for said opening ropes at the upper end of said intermediate element the length of which and the position of the fixation points of the opening ropes on said grab head being se lected so that the running block effect of the opening ropes ceases automatically when said grab rods have come in contact with said stops.

PAUL NEFFENDORF, GEN. GAERTNER.

Hill 

